In what form do plants primarily take up nitrogen from the soil?

Plants primarily take up nitrogen from the soil in the form of nitrates. Nitrates (NO3-) are a soluble form of nitrogen that plants can easily absorb through their roots. This form of nitrogen is crucial for plant growth as it is directly involved in the synthesis of amino acids, proteins, and various other essential compounds.

While ammonium (NH4+) is also taken up by plants, it is less common in soil due to its tendency to bind with soil particles, making nitrates the more prevalent and accessible form for most plants. Nitrogen gas (N2) and organic nitrogen are not directly usable by plants without prior conversion processes performed by certain soil microorganisms. Thus, the predominant way through which plants acquire nitrogen is through the uptake of nitrates, highlighting the importance of nitrification and the nitrogen cycle in ecosystems.